PREAMPLIFIER, OPTICAL RECEIVER, OPTICAL TERMINATION DEVICE, AND OPTICAL COMMUNICATION SYSTEM

摘要

A current-side flow circuit (230) which passes a portion of a photocurrent that is output from a light-receiving element (100) is connected to an input terminal of a current-to-voltage conversion amplifier circuit (210). The voltage resulting from level conversion of an output voltage at a voltage level conversion circuit (240) is input to the current-side flow circuit (230) so that the current-side flow circuit (230) is turned on with a photocurrent that is smaller than the photocurrent with which a diode (220) that is connected in parallel to a feedback resistor (212) of the current-to-voltage conversion amplifier circuit (210) is turned on. As a result, in accordance with the magnitude of a photocurrent corresponding to a received light level, current/voltage conversion gain is switched in 3 stages.